The subject matter disclosed herein relates generally to systems and methods for computed tomography (CT) imaging, and for selection of bowtie filtration configuration and/or determination of attenuation of an object to be imaged.
In CT imaging, an X-ray source may be rotated around an object to obtain imaging information. A bowtie filter may be interposed between the X-ray source and the object to be imaged, with the bowtie filter configured to absorb radiation (e.g., from a fan-shaped X-ray beam) to control the distribution of radiation received by the object, for example across a width of the object. A collimator may be used in conjunction with the bowtie filter to direct radiation from the source to the object to be imaged, and to limit radiation directed to the object to a desired field of view.
Different configurations of bowtie filters may be available. For example, differently sized bowtie filters may be configured for differently sized patients. However, due to the current use of a finite number of filters with a largely variable patient population, selection of the appropriate filter may be difficult for patients that do not clearly fall within a given size category associated with the filters (e.g., a patient on or near a borderline size category). Further still, depending on internal structure of the patient and/or a scanning procedure to be performed, the most appropriate bowtie filter may be from a different size category than may be conventionally associated with the patient. Selection of an appropriate bowtie filter may involve complicated interrelationships between numerous parameters, making manual selection by operators prone to error and/or inefficiency.
Further, even if a bowtie configuration may be determined to satisfy certain criteria, the bowtie configuration may still result in poor image quality and/or dosage levels if the object to be imaged is not positioned properly. For example, conventional systems may make centering an object to be imaged (e.g., patient) difficult to achieve and/or to determine. For example, misunderstanding of system design implications or difficulty of visually determining relative positioning by an operator may result in improper positioning. Additionally or alternatively, centering may not be feasible in some instances (e.g., due to individual patient constraints). Such mis-positioning may lead to sub-optimal patient positioning, and sub-optimal image quality.
Further, attenuation of an object (e.g., the ability of the object to attenuate X-rays from a source during passage of X-rays from the source to a detector) may be determined or estimated, for example, using a scout scan, to control performance of the scan. However, conventional approaches are susceptible to error from variabilities or inconsistencies regarding patient positioning during a scout scan, resulting in inaccurate attenuation estimates and reduced quality and/or convenience of imaging.